What is the Asian Carps role in the health of our water?
Fortunately, regarding the Great Lakes and western Lake Erie, almost none at this moment. The popular-press term “Asian carp” is a little misleading. Depending upon context, that term is usually used to refer to two to four different species of fish. Those that are currently receiving the most press are silver and bighead carps (silver carp is the jumper). These two species are large, efficient planktivores, meaning they eat plankton, the base of aquatic food webs. In doing so so efficiently, they have the potential to thin the flow of energy (reducing the amount of available food) to animals all the way up the food web, from the plankton all the way up to the large game fish that people value. There do not appear to be any reproducing populations of these invasive carps in the Great Lakes watershed at this time.
In general, the Great Lakes are not very productive: deep, cold, nutrient-poor, and not the kinds of plankton-rich environments that silver and bighead carps like. Also, there is some question whether or not these carps, which are big-river fish in their home range, could ever reproduce in the cold and relatively short rivers of the upper Great Lakes. The most obvious exception, the one place where an invasion by these animals may be most likely to take hold and substantially change the ecosystem, would be the western basin of Lake Erie. Lake Erie is the most productive and plankton-rich of the Great Lakes and thus has the most to lose. Even here, it is not known how often conditions would be right for these fishes to reproduce in our larger rivers, like the Maumee. It would be best to not find out and to work to prevent their invasion to the Great Lakes and tributaries.
Another species that is sometimes lumped as an “Asian carp” is the grass carp or white amur. These fish mostly eat aquatic plants. Sterile fish of this species, fish that are unable to reproduce, are raised in hatcheries for use by pond owners to control excessive vegetation. It is illegal in Ohio to possess a grass carp that is capable of reproduction. This is because a reproducing population could be very damaging to wetland habitats.
Eugene C. Braig IV, Ohio Sea Grant College Program